Toner is the term used to generally describe the particulate material that is applied and fused to paper by an electrographic or xerographic reproduction system to reproduce text and images. The toner is typically stored in a container or cartridge housed within the electrographic reproduction system. The cartridge or container may have a body with an internal volume within which the toner is stored. Prior to installation in an electrographic reproduction system, the toner cartridge or container must be filled with toner particulate matter.
The process for filling a toner container with toner currently requires that the toner be transported from a toner supply hopper into the container by a rotating auger. The auger is a spiral shaped mechanical part which pushes particles of toner inside a fill tube by direct mechanical contact. The nature of this mechanical contact process creates substantial limitations on the accuracy, efficiency, and speed of the toner container filling operation. The speed of the toner movement in the fill tube is proportional to the speed of rotation of the auger and is limited by the heat produced by friction occurring between the auger and toner. High auger speed causes the toner to melt, particularly for low melt toner, such as the one disclosed in U.S. Pat. No. 5,227,460 to Mahabadi et al. the relevant portions thereof are herein expressly incorporated by reference.
To more effectively and efficiently fill toner containers, the rotating augers used to transport the toner from hoppers are relatively large. The large augers provide for high volume toner flow and thus improve productivity in a fill line. When utilizing such fill lines for small, low cost copiers and printers, fill problems occur because the openings in the toner containers for small copiers and printers are small and may have an irregular shape. Furthermore, the openings may be located at a position on the container that is not centrally located on the container. As a consequence, smaller filling tubes and augers are required to fit the small toner container fill openings. Efficiency for filling toner containers housed in small copiers and printers is important because these devices produce copies in higher quantities, which requires that the containers be filled with as much toner as possible.
Problems with efficient toner filling are also apparent in small and medium cost multi-colored highlight or full color printers and copiers. The toner containers for color toner typically are smaller than those for black toner and also more typically have an irregular shape. Also, color toners have been developed with smaller particle size of, for example, 7 microns or less. The smaller particles of the colored toners do not flow as easily through toner hoppers as larger particles and are not easily translated from the hopper by the augers.
The problems associated with controlling the filling of toner containers are due primarily to the properties of the toner. There are two different types of developing systems known as one component and two-component systems. In one-component developing systems, the developer material is toner made of particles of magnetic material, such as iron, that are embedded in a black plastic resin. The iron enables the toner to be magnetically charged. In two- component systems, the developer material is comprised of toner which consists of small polymer or resin particles, a color agent, and a carrier which consists of roughly spherical particles or beads usually made of steel. An electrostatic charge between toner particles and carrier beads causes toner particles to cling to carrier beads in the development process. Control of the flow of these small, abrasive and easily charged particles is very difficult.
The toner particles used in one-component and two-component systems do not flow easily and they tend to cake and bridge within the supply hopper. This limits the flow of toner through the small tubes that are required for supplying the smaller openings in toner containers for small copiers and printers. Also, this tendency to cake and bridge may cause air gaps to form in the container resulting in partial filling of the container. Attempts to improve the flow of toner have also included the use of an external vibrating device to loosen the toner within the hopper. These vibrators are energy intensive, costly, but they do not necessarily produce consistently effective filling of the toner containers. Furthermore, they tend to cause the toner to cloud causing dirt to accumulate around the filling operation.
Difficulties have also occurred in efforts to start and stop quickly the flow of toner from the hopper during high speed production operations. An electromagnetic toner valve has been developed as described in U.S. Pat. Nos. 5,839,485 and 5,685,348, both of which issued to Wegman et al. and they issued on Nov. 24, 1998 and Nov. 11, 1997, respectively. Both of these patents are assigned to the same assignee as this application and the disclosures thereof are hereby expressly incorporated herein by reference in their entireties. The electromagnetic valve is limited for use with toner that can be magnetized such as that described for use with one component development systems.
Attempts have been made to fill toner containers having small toner fill openings by utilizing adapters positioned on the end of the toner filling auger that has an inlet corresponding to the size of the auger and an outlet corresponding to the opening in the toner container. Clogging with toner, particularly when attempting to increase toner flow rates and when utilizing toners with smaller particle size, for example, color toners having a particle size of 7 microns or less, has been found to be a perplexing problem. The adapters that are fitted to the augers, thus, tend to clog with toner. The flow rates through such adapters are unacceptably low. Further, the use of these adapters may create problems with maintaining a clean atmosphere free of toner at the site of the filling operation.
The following disclosures relate to various aspects of toner container filling systems and the problems encountered with filling toner containers with toner particles: U.S. Pat. No. 5,531,253 to Nishiyama et al. that issued on Jul. 2, 1996, U.S. Pat. No. 5,839,485 to Wegman et al. that issued on Nov. 24, 1998, U.S. Pat. No. 5,685,348 to Wegman et al. that issued on Nov. 11, 1997, U.S. Pat. No. 5,947,169 to Wegman et al that issued on Sep. 7, 1999, and U.S. Pat. No. 5,909,829 to Wegman et al that issued on Jun. 8, 1999. Portions of the foregoing disclosures may be briefly summarized as follows:
U.S. Pat. No. 5,531,253 discloses a cleaner for cleaning the nozzle portion of a powder filling apparatus by equally evacuating the inside and the outside of the container and dropping powder through the nozzle portion into the container simultaneously with the raising the pressure outside the container.
U.S. Pat. No. 5,838,485, entitled “Electromagnetic Valve and Demagnetizing Circuit” discloses a method and apparatus for filling a container with a magnetic material using an electromagnetic valve and a demagnetizing circuit to control the flow and properties of the material. In the filling process, the auger located inside of the fill tube rotates and moves the material through the fill tube. When the container is filled, the auger stops rotating and the electromagnetic valve actuated. The electromagnetic valve supplies a magnetic field which holds the material in place, plugging the fill tube with the material as the filled container is removed and replaced with a new container to be filled. When the electromagnetic valve is switched off, a demagnetizing circuit is activated. After the material is demagnetized, the auger is switched on and the material flows again into the container.
U.S. Pat. No. 5,685,348 discloses a method and apparatus for filling a container with toner using a series of traveling magnetic fields to control the flow of toner from a supply of toner to the container. Initially, an empty container is placed under a fill tube through which toner is supplied to the container. In the filling process the traveling magnetic fields, which are supplied by turning on and off a series of solenoids, and gravity cause toner from the toner supply to move through the fill tube. When a solenoid is turned on toner particles are attracted to its magnetic field where a plug of toner is formed. The solenoids are controlled so that a discrete amount of toner is supplied in each on/off cycle of the solenoids. The solenoid on/off cycle is repeated until the container is filled with toner. When the container is filled, the appropriate solenoid is activated so that a plug of toner stops the flow of toner in the fill tube. The filled container is removed from the fill tube and an empty container is put in its place so that the solenoid on/off cycle may begin again.
U.S. Pat. No. 5,947,169 entitled “Oscillating Valve for Powders” discloses a method for filling a powder container. The method includes the steps of placing a first powder container to be filled in filling relationship to a discharge feature in the vessel, directing the powder in the vessel toward a member located at least partially within the vessel, the member defining a restriction therein such that the powder clogs within the restriction, mechanically exciting the powder at least adjacent the restriction to improve the flow properties of the powder so as to unclog the powder within the restriction, dispensing powder through the restriction, through the discharge feature and into the first container, stopping the mechanical excitation of the powder so as to clog the restriction with the powder, removing the first container from the vessel, and placing a second container to be filled in filling relationship to the vessel.
U.S. Pat. No. 5,909,829 entitled “Vibratory Filler for Powders” discloses a method for filling a powder container. The method includes the steps of placing a first powder container to be filled in filling relationship to a supply of powder in a vessel, mechanically exciting the powder in the vessel to improve its flow properties, dispensing powder from the vessel into the first container, removing the first container from the vessel, and placing a second container to be filled in filling relationship to the vessel.
All of the above-referenced patents are hereby expressly incorporated by reference herein in their entireties.
While the problems regarding toner flow have been addressed by the solutions set forth in these patents, they do not address the efficient use of the internal volume in the container. As toner flows into a container, air is pushed out of the container. The fit between the filling tube and the filling opening typically enables air to flow out of the container during a filling operation without interfering with the flow of toner particles into the container. However, replacement of the air in the container with toner particles is not completely efficient. That is, air becomes trapped between toner particles and this air reduces the amount of toner that is stored in the container. If this air were removed from the internal volume of the container, more toner could be stored in the container.